The present invention relates to the incorporation of a bactericide and a fungicide into building materials, more specifically into cementitious compositions such as grout, mortar, monolayer render and ceramics, in order to reduce microbial contamination by bacteria and fungi, thereby avoiding the appearance of dark spots in these materials. The cementitious compositions containing a bactericide together with a fungicide which are dispersed in an inorganic carrier material or matrix showed a significant reduction of microbial contamination even when exposed to damp environment or water.
Ceramic parts are considered one of the most washable surfaces available and are applied on the walls and floor in a wide variety of places. Currently, these parts are fixed to the ground using grout, mortar and monolayer render, whose purpose is to fill the spaces between the adjacent pieces. Usually, grouts and mortars are formulated from a mixture of Portland cement, mineral aggregates and additives. During their preparation only water is added.
In recent decades, great efforts have been made to the development of building materials with high quality and low costs. Despite the benefits and advantages of surfaces covered with ceramics, problems of contamination by micro-organisms are recurrent. They can cause chemical and physical changes producing aesthetic problems, structural degradation and fragmentation of the coating. Furthermore, the frequent cleaning of the surface can lead to a reduction in the life of such cementitious compositions. Since there are difficulties in cleaning and they are contaminated with time, they must be removed physically or mechanically, which is arduous and expensive.
Materials used in construction as grouts, mortars and monolayer render contain a large variety of organic and inorganic constituents. Several of these components can be used by micro-organisms for their growth and development, which makes these materials susceptible to microbiological contamination.
Areas that dry slowly and are always in contact with water and moisture are favorable environments (substrata) for growth of filamentous fungi. Such areas, like as walls, ceilings and floors of bathrooms, showers, swimming pools, changing rooms and food processing areas, need a coating that helps in moisture control and protection of the substratum. Paint, tile, grout and mortar are applied to the surface for protection and ensure a good appearance to the environment.
The development of micro-organisms on surfaces changes their appearance as many micro-organisms contain pigments that change the environment color. The emergence of dark spots on the surface of these materials is often characterized by the growth of filamentous fungi.
One of the problems related to the use of biocides in coatings is leaching. It has been demonstrated that many biocides can be leached when exposed to water and damp environment. The leaching process decreases the amount of biocide in the substratum, enabling the micro-organisms to grow.
These cementitious-based construction materials exhibit a high pH, but this is not sufficient to prevent micro-organisms attack, since the bacteria growing on them can promote a decrease in pH. The decrease in pH, consequently, causes a favorable environment for micro-organisms' growth. Fungi are micro-organisms that grow in relatively low pH. The decrease in pH by the bacteria makes these cement compositions more susceptible to fungal growth.
The use of fungicides in different types of construction materials is known in the art.
U.S. Pat. No. 4,556,426 relates to a Portland cement base with a halogenated aromatic dinitrile added as an active fungicidal ingredient. The resulting fungicide grout composition prolonged leach-life characteristics.
U.S. Pat. No. 5,421,867 discloses cementitious-based products, such as mortar, grout, backerboard and stucco, that are comprised of Portland cement as a common ingredient combined with optional fillers and additives with the addition of an effective antimicrobial agent.
US-2008/0281017 A1 relates to the use of biocide-containing, water-redispersible polymer powder compositions in mineral building compositions.
There are several documents that have combined antimicrobials into various industrial products.
US-2011/0077278 A1 discloses a mixture of 3-iodopropynyl-N-n-butylcarbamate (IPBC) and 2-n-N-butyl-1,2-benzisothiazolin-3-one (BBIT) for use as a fungicide and growth inhibitor in industrial applications.
US-2008/0206295 A1 teaches formulations based on 3-iodo-2-propynyl butyl carbamate (IPBC).
U.S. Pat. No. 6,133,300 discloses antimicrobial mixtures of 1,2-benzisothiazolin-3-one (BIT) and 1,3-bis (hydroxymethyl)-5-dimethylhydantoin (DMH) used to protect a substratum from attack by micro-organisms. The composition can be used broadly in industrial systems.
The IPBC (3-iodo-2-propynyl butyl carbamate) is a biocide commonly used to prevent fungus development and is highly effective against a wide variety of fungal species. IPBC can be used in various industrial applications, for example, paints, construction materials, surfactants, wood, plastics, textiles, oils, emulsions and cosmetics.
Isothiazolinones are bactericides widely used in industry to preventing bacterial growth in several applications. They are used as environmental biocides as well as preservatives for filler, pigment-systems and in-can protection.
U.S. Pat. No. 5,219,875 discloses a composition comprising 1,2-benzisothiazolin-3-one (BIT) and iodopropargyl butylcarbamate (IPBC) used for controlling microbes.
The state of the art presented above does not present any teaching about the biocide leaching problem and its prevention. The problem to be solved by the instant invention is to provide a biocide composition which is less susceptible to leaching and which may be used for cementitious compositions and cementitious-based products.
Accordingly, to overcome the shortcomings of prior art, it is an object of the subject invention to prevent bacterial and fungal infestation of cementitious compositions and cementitious-based products by using biocides deposited in inorganic matrices that make the biocides less leachable, thereby preventing the discoloration of such compositions and products.